So here it goes...

This is my first 400 and I'm really looking forward to breathing new life into this blower. As is, it sounds like broken glass when cranked and grinds to a halt.

Someone along the line did some "work" on it. The disassembly couldn't have been any easier! BUT every inch was CAKED with grease and It had NO bearings on either side of the front shaft and 1 broken caged bearing on the rear shaft. The worm shaft had the bearings but man no wonder why it grinds to a halt.

Gears are in good shape.

 

All apart soaking in ATF/Acetone. I left the gears and shafts in place. 

I'll update as I go.

Since the brass/bronze gears appear to be in good shape it is probable that you will be able to successfully restore it.  It sounded kind of "grindy" but that may just be all the gruck and lack of some bearings.  Good luck.

"By hammer and hand all arts do stand."

That ATF/Acetone mix works like a charm. Brought everything down to bare metal and cut right through all the grease. 

The races are in good shape, some wear, I have the replacement bearings and 30wt oil. I just need to fab a handle and reassemble.  Then make a stand and paint.  Color scheme TBD.

The grease was the biggest part of the problem. Those blowers are designed to run in oil. A good oil is chainsaw bar oil with some STP mixed in or 30 wt non-detergent motor oil. Just enough oil for the lower gear teeth to run in and it's a splash oil system, the lower gear will distribute the oil to all the rest of the bearings and gears. Too much oil and they leak like a sieve.

I'm having one issue maybe someone has an answer to. Reattaching the fan assembly.

From all videos, pics etc it appears as though the fan assembly simply threads on the worm gear all the way to the grease cap. When I do that and start cranking the fan threads tighter causing the worm gear to become so tight it won't spin.

Seems like I'm missing something obvious. I have two indexed washers left and two nuts, one being thinner than the other. Obviously one set goes on after the fan. What about the other set?

Thanks!

Also if it goes according to what I've seen I'd have a left over washer and nut. It spun before so i'm doing something wrong. I don't know if there's slight variations from blower to blower or if someone along the line altered it or what. 

Figured it out.

All done and well worth it!  I'll be keeping an eye out for an original stand or at least the mounting bracket. I'll fab a decent one for the time being.

   

Fantastic job! 

I personally would recommend spinning the blower clockwise, so that the bronze gear is pushed down, meshing with the spiral gear better over time.
Turning counter clockwise (as your red arrow points) pulls the bronze gear up and as the bronze bushings wear, the mesh will decrease. 
And thus I recommend reversing the arrow on your blower for a longer life. 

Outstanding restoration, I agree with TechnicusJoe.

Another hint to make using it more comfortable is if you have access to a wood lathe, turn a handle like the one that I turned and found to be better than a straight wood one. Could be done with a drill press and wood rasp.

Thanks!  Great points thank you, I'll reverse the direction and the handle was a bit rushed since it was the last thing but that makes sense too, I have the tools to make another. 

Sweet overhaul!!!!!

It was working great BUT one of the inner races cracked into 3 pieces. I'm guessing the new bearings were too much stress on it. I hate to spend the money on a donor blower. 

I’ll look in my pile, I’ve got like six or seven 400s am some are just junkers 

All done. Just missing an inner race which I should receive shortly!